Yokai

In classical texts, the supernatural appears mainly as oni (demons) and mononoke, spirits that cause illness and misfortune; in The Tale of Genji a jealous living spirit possesses and kills a rival. Heian aristocrats avoided unlucky directions and hired onmyōji, diviners of yin and yang, to ward off such forces. Medieval picture scrolls show the Night Parade of One Hundred Demons (hyakki yagyō), a procession of monsters through the capital at night.

Many such beings are ambivalent rather than evil. The folklorist Yanagita Kunio (1875–1962) proposed that yōkai were often 'fallen' kami – deities who, no longer properly worshipped, appeared in threatening form. Whether or not that theory holds in every case, yōkai and kami share a world in which nature, places and objects possess power that must be respected. Old tools were said to become tsukumogami, animated objects, after a hundred years, which encouraged people to treat or dispose of them properly.

Hundreds of yōkai are recorded, many known only in a single valley. A few have become familiar throughout Japan, each tied to a particular kind of place or fear.

In the Edo period, printing and urban leisure turned yōkai from objects of fear into objects of curiosity and play. Groups gathered on summer nights for hyakumonogatari kaidankai, telling a hundred ghost stories and extinguishing a candle after each one. Kabuki staged spectacular ghost plays such as Tsuruya Nanboku's Yotsuya Kaidan (1825), and woodblock artists including Katsushika Hokusai and Utagawa Kuniyoshi produced memorable images of spirits and monsters.

The decisive figure was Toriyama Sekien (1712–1788), whose illustrated encyclopaedia Gazu Hyakki Yagyō (1776) and its sequels gave hundreds of yōkai a fixed name and appearance – some drawn from folklore, some from Chinese sources, some apparently invented as visual puns. His books became the reference on which later artists, and eventually manga, drew.

Modernising Meiji Japan viewed yōkai with suspicion. The philosopher Inoue Enryō (1858–1919) founded what he called yōkaigaku, 'monsterology', collecting reports of the supernatural in order to explain them rationally and free people from superstition. Almost at the same time, Lafcadio Hearn (Koizumi Yakumo) retold Japanese ghost stories for Western readers in Kwaidan (1904).

Yanagita Kunio took the opposite approach. His Tōno Monogatari (1910), a collection of legends from a mountain basin in Iwate, treated tales of kappa, zashiki-warashi and mountain people as evidence of an older folk religion worth recording. Japanese folklore studies (minzokugaku), which he founded, made yōkai a serious field of research; since the 1980s the anthropologist Komatsu Kazuhiko and the International Research Center for Japanese Studies in Kyoto have extended it with large databases of local traditions.

The manga artist Mizuki Shigeru (1922–2015) did more than anyone to make yōkai part of post-war popular culture. His series GeGeGe no Kitarō, about a one-eyed yōkai boy, began in the 1960s and has been adapted for television in every decade since; his illustrated yōkai encyclopaedias fixed their image for new generations. His home town of Sakaiminato in Tottori Prefecture lines a street with over a hundred bronze yōkai statues and runs a museum in his honour.

Yōkai populate anime and games from Studio Ghibli's Pom Poko and Spirited Away to the Yo-kai Watch franchise, and urban legends such as the slit-mouthed woman (kuchisake-onna) and Hanako of the school toilet show that new yōkai continue to appear. In rural Japan older traditions endure in ritual form: the masked Namahage of the Oga Peninsula in Akita, who visit homes on New Year's Eve to admonish lazy children, belong to the visiting-deity rites (raihōshin) inscribed on UNESCO's Intangible Cultural Heritage list in 2018.